The present invention relates generally to dental appliances and restorations and particularly to prefabricated components for use in dental appliances and restorations and methods of manufacture thereof and more particularly to prefabricated hybrid components for use in dental appliances and restorations.
Dental appliances and restorations such as bridges, crowns, dentures and the like may be used to restore a missing tooth and retain natural teeth in position and prevent migration subsequent to orthodontic treatment. Structural components used in these appliances often include wires, bars, posts, shells, beams, clasps and other shapes. The shape of the structural components may vary depending upon the requirements of the appliance.
The manufacture of frameworks for bridges using current techniques can be time consuming and labor intensive. Some techniques may involve taking uncured fiber-reinforced composite material and forming uncured strips of the fiber-reinforced composite material into a bridge framework upon a dental cast. The procedure can be an involved and complex process depending upon the final shape desired. Moreover, dental technicians and practitioners may use less than the optimum amount of fiber for reinforcement when preparing the dental framework in order to reduce the cost which may lead to low strength and therefore potential fracture of the final product. Furthermore, the complexity of the dental appliance may require a certain dexterity to achieve optimal properties that may not be achievable by some technicians and practitioners. The use of metals, alloys and ceramics which exhibit high flexural strengths such as 300 MPa and higher reduces light transmission and thus affects the aesthetic appearance.
There remains a need to simplify the process of fabricating dental appliances to reduce time and labor involved in the preparation process and to provide appliances having optimum properties. It is desirable to reduce the risk of contamination during the fabrication of dental appliances. It is desirable to maintain strength of dental appliances without sacrificing aesthetic and light transmitting properties. It is beneficial to faciliate the dental applicance fabrication process in the dental laboratory and at the dentist office.
These and other objects and advantages are accomplished by the present invention wherein preshaped, prefabricated cured components are prepared in a variety of shapes and sizes to be used in the fabrication of dental appliances. Preferably the components are fabricated of a fiber-reinforced composite material comprising fibers impregnated with a polymeric matrix. After impregnation of a fibrous material with a polymeric matrix, the resultant fiber-reinforced composite material is shaped and is partially or fully cured to the point of sufficient hardness to provide a component for use in the fabrication of dental appliances including but not limited to orthodontic retainers, bridges, space maintainers, tooth replacement appliances, dentures, posts, crowns, posts, jackets, inlays, onlays, facings, veneers, facets, implants, abutments, splints, partial crowns, teeth, cylinders, pins, and connectors.
In one embodiment herein, the components are in the shape of a structure for immediate use in the fabrication of a dental appliance. The structural components are formed into any known shapes useful in the fabrication of a dental appliance or restoration. Preferably, the structural components are in the shape of bars, rods or pontics. The pontics have interproximal extensions and may be single-unit or multiple-unit useful in the fabrication of frameworks for bridges. The structural components may be xe2x80x9cready-to-usexe2x80x9d for immediate use in the fabrication of a dental appliance or restoration or may be further modified, for example by cutting, carving, etching, abrading or grinding prior to using in the fabrication of a dental appliance or restoration.
In another embodiment herein, the components are formed into pieces or blocks of fiber-reinforced composite material. The blocks of material are useful in making a variety of shapes and sizes and may be modified by a variety of methods including but not limited to machining, carving, cutting, grinding, etching or abrading.
The bars, rods, pontics and blocks may be of any cross-sectional configuration effective to provide strength and stiffness to the finished dental appliance.
In yet another embodiment herein, preshaped, prefabricated hybrid components are provided wherein at least one section of the component is cured and at least one section of the component is uncured. The component is a xe2x80x9chybridxe2x80x9d component due to the combination of a cured or partially cured section or sections with an uncured or slightly partially cured section or sections. The hybrid components are useful in the fabrication of dental appliances or restorations whereby the uncured or slightly partially cured sections are cured at the point of insertion in the patient""s mouth providing ease of application due to the flexibility and adaptability of the uncured/slightly partially cured sections and optimum bonding of the uncured/slightly partially cured component to the patient""s existing teeth and/or to other cured, partially cured or uncured components. The cured/partially sections of the hybrid components are substantially hard and are not amenable to bending, but may be modified by a variety of methods used on hard components without disrupting the structural integrity of the component including machining, carving, cutting, grinding, etching, and abrading. The uncured/slightly partially cured sections of the hybrid components are very soft and flexible and may be modified by a variety of methods including forming, shaping, contouring, adjusting, and etching.
In one method of manufacture, the components are made after the impregnation of the fibers with a polymeric matrix. After impregnation of the fibers, the resultant composite material is formed into, for example, a long bar and cured or polymerized to a hardness whereby the bar may be cut and/or machined without deforming the structural integrity of the bar. The bar is preferably cut into short segments and is ready for use in the fabrication of dental appliances. The bars may be used as is or may be further modified by cutting, grinding, machining, and the like to provide a specifically shaped or customized component. The component may further be veneered with a composite material such as a particulate-filled composite to develop clinically acceptable anatomy.
In another method of manufacture, prefabricated preshaped hybrid components are manufactured using special molds to permit curing in limited sections of the components. Filled (fiber, particulate or filler or a reinforcing component) composite material is inserted into a section of a lower mold piece or half to be cured. The material is cured or partially cured and more composite material, preferably, fiber-reinforced composite material is inserted into various sections of the mold. The fiber-reinforced composite material is not cured. Thereafter, additional composite material (fiber, particulate, filler or other reinforcing component) is placed on the section of material that was originally cured or partially cured. The lower mold piece is then covered with an upper mold piece or pieces to form and shape the material therein to the desired shape. The upper mold pieces covering the sections of the mold having composite material to be cured are removed leaving those upper mold sections covering the composite material to remain uncured. The uncovered mold section having composite to be cured is subsequently light cured. The resultant component is removed from the mold pieces and the uncured sections of the component are covered with a protective sleeve to prevent contamination and curing until the component is to be used in the fabrication of a dental restoration or appliance.